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Share-based payments - Charge has been recognised in income statement for Rio Tinto's share-based incentive plans, and the related liability (for cash-settled plans) (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Line Items]      
Liability at the end of the year $ 15 $ 1  
Charge recognised for the year 91 116 $ 128
Equity-settled plans [member]      
Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Line Items]      
Charge recognised for the year 88 116 $ 128
Cash-settled plans [member]      
Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Line Items]      
Liability at the end of the year 15 $ 1  
Charge recognised for the year $ 3